EPDCCH resource and quasi-co-location management in LTE

ABSTRACT

A method, an apparatus, and a computer program product for wireless communication are provided. In an aspect, the apparatus may determine at least a first and second resource set configured for a control channel and may determine a common set of aggregation levels for the first and second resource sets. The apparatus may further determine first rate-matching parameters for the first resource set and second rate-matching parameters for the second resource set, and may process the control channel using the common set of aggregation levels and the first and second rate-matching parameters.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a divisional of U.S. patent application Ser. No.14/021,980 entitled “EPDCCH RESOURCE AND QUASI-CO-LOCATION MANAGEMENT INLTE” and filed on Sep. 9, 2013 and U.S. Provisional Application Ser. No.61/722,097 entitled “EPDCCH RESOURCE AND QUASI-CO-LOCATION MANAGEMENT INLTE” and filed on Nov. 2, 2012, each which is expressly incorporated byreference herein in its entirety.

BACKGROUND

Field

The present disclosure relates generally to communication systems, andmore particularly, to systems that employ coordinated multipointwireless transmissions.

Background

Wireless communication systems are widely deployed to provide varioustelecommunication services such as telephony, video, data, messaging,and broadcasts. Typical wireless communication systems may employmultiple-access technologies capable of supporting communication withmultiple users by sharing available system resources (e.g., bandwidth,transmit power). Examples of such multiple-access technologies includecode division multiple access (CDMA) systems, time division multipleaccess (TDMA) systems, frequency division multiple access (FDMA)systems, orthogonal frequency division multiple access (OFDMA) systems,single-carrier frequency division multiple access (SC-FDMA) systems, andtime division synchronous code division multiple access (TD-SCDMA)systems.

These multiple access technologies have, been adopted in varioustelecommunication standards to provide a common protocol that enablesdifferent wireless devices to communicate on a municipal, national,regional, and even global level. An example of an emergingtelecommunication standard is Long Term Evolution (LTE), UTE is a set ofenhancements to the Universal Mobile Telecommunications System (UMTS)mobile standard promulgated by Third Generation Partnership Project(3GPP). It is designed to better support mobile broadband Internetaccess by improving spectral efficiency, lowering costs, improvingservices, making use of new spectrum, and better integrating with otheropen standards using OFDMA on the downlink (DL), SC-FDMA on the uplink(UL), and multiple-input multiple-output (MIMO) antenna technology.However, as the demand for mobile broadband access continues toincrease, there exists a need for further improvements in LTEtechnology. Preferably, these improvements should be applicable to othermulti-access technologies and the telecommunication standards thatemploy these technologies.

SUMMARY

In an aspect of the disclosure, a method, a computer program product,and an apparatus are provided. In an aspect, the apparatus may receive aset of configurations for an enhanced physical downlink control channel(EPDCCH) that are tied to a set of configurations received for aphysical downlink shared channel (PDSCH). Each configuration in the setof configurations for the PDSCH may define at least one of a startingsymbol, rate-matching information, or a quasi-co-location (QCL)indication and the set of configurations for the EPDCCH may be a subsetfrom among the set of configurations for the PDSCH. The apparatus maythen receive and process the EPDCCH based on at least one configurationfrom the set of configurations for the EPDCCH.

In an aspect, the apparatus may determine at least a first resource setand a second resource set configured for a control channel and maydetermine a common set of aggregation levels for the first resource setand second resource set. The apparatus may determine first rate-matchingparameters for the first resource set and second rate-matchingparameters for the second resource set and may process the controlchannel using at least the common set of aggregation levels and thefirst rate-matching parameters and second rate-matching parameters.

In an aspect, the apparatus may determine whether a starting symbol ofan EPDCCH is an initial symbol in a subframe and may refrain fromdecoding a subset of legacy control channels in the subframe when thestarting symbol of the EPDCCH is the initial symbol in the subframe.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a diagram illustrating an example of a network architecture.

FIG. 2 is a diagram illustrating an example of an access network.

FIG. 3 is a diagram illustrating an example of a DL frame structure inLTE.

FIG. 4 is a diagram illustrating an example of an UL frame structure inLTE.

FIG. 5 is a diagram illustrating an example of a radio protocolarchitecture for the user and control planes.

FIG. 6 is a diagram illustrating an example of an evolved Node B anduser equipment in an access network.

FIG. 7 is a diagram illustrating a range expanded cellular region in aheterogeneous network.

FIG. 8 is a flow chart of a method of wireless communication.

FIG. 9 is a flow chart of a method of wireless communication.

FIG. 10 is a flow chart of a method of wireless communication.

FIG. 11 is a flow chart of a method of wireless communication.

FIG. 12 is a conceptual data flow diagram illustrating the data flowbetween different modules/means/components in an exemplary apparatus.

FIG. 13 is a diagram illustrating an example of a hardwareimplementation for an apparatus employing a processing system.

FIG. 14 is a flow chart of a method of wireless communication.

FIG. 15 is a flow chart of a method of wireless communication.

FIG. 16 is a flow chart of a method of wireless communication.

FIG. 17 is a conceptual data flow diagram illustrating the data flowbetween different modules/means/components in an exemplary apparatus.

FIG. 18 is a diagram illustrating an example of a hardwareimplementation for an apparatus employing a processing system.

DETAILED DESCRIPTION

The detailed description set forth below in connection with the appendeddrawings is intended as a description of various configurations and isnot intended to represent the only configurations in which the conceptsdescribed herein may be practiced. The detailed description includesspecific details for the purpose of providing a thorough understandingof various concepts. However, it will be apparent to those skilled inthe art that these concepts may be practiced without these specificdetails. In some instances, well known structures and components areshown in block diagram form in order to avoid obscuring such concepts.

Several aspects of telecommunication systems will now be presented withreference to various apparatus and methods. These apparatus and methodswill be described in the following detailed description and illustratedin the accompanying drawings by various blocks, modules, components,circuits, steps, processes, algorithms, etc. (collectively referred toas “elements”). These elements may be implemented using electronichardware, computer software, or any combination thereof. Whether suchelements are implemented as hardware or software depends upon theparticular application and design constraints imposed on the overallsystem.

By way of example, an element, or any portion of an element, or anycombination of elements may be implemented with a “processing system”that includes one or more processors. Examples of processors includemicroprocessors, microcontrollers, digital signal processors (DSPs),field programmable gate arrays (FPGAs), programmable logic devices(PLDs), state machines, gated logic, discrete hardware circuits, andother suitable hardware configured to perform the various functionalitydescribed throughout this disclosure. One or more processors in theprocessing system may execute software. Software shall be construedbroadly to mean instructions, instruction sets, code, code segments,program code, programs, subprograms, software modules, applications,software applications, software packages, routines, subroutines,objects, executables, threads of execution, procedures, functions, etc.,whether referred to as software, firmware, middleware, microcode,hardware description language, or otherwise.

Accordingly, in one or more exemplary embodiments, the functionsdescribed may be implemented in hardware, software, firmware, or anycombination thereof. If implemented in software, the functions may bestored on or encoded as one or more instructions or code on acomputer-readable medium. Computer-readable media includes computerstorage media. Storage media may be any available media that can beaccessed by a computer. By way of example, and not limitation, suchcomputer-readable media can comprise RAM, ROM, EEPROM, CD-ROM or otheroptical disk storage, magnetic disk storage or other magnetic storagedevices, or any other medium that can be used to carry or store desiredprogram code in the form of instructions or data structures and that canbe accessed by a computer. Combinations of the above should also beincluded within the scope of computer-readable media.

FIG. 1 is a diagram illustrating an LTE network architecture 100. TheLTE network architecture 100 may be referred to as an Evolved PacketSystem (EPS) 100. The EPS 100 may include one or more user equipment(UE) 102, an Evolved UMTS Terrestrial Radio Access Network (E-UTRAN)104, an Evolved Packet Core (EPC) 110, a Home Subscriber Server (HSS)120, and an Operator's IP Services 122. The EPS can interconnect withother access networks, but for simplicity those entities/interfaces arenot shown. As shown, the EPS provides packet-switched services, however,as those skilled in the art will readily appreciate, the variousconcepts presented throughout this disclosure may be extended tonetworks providing circuit-switched services.

The E-UTRAN includes the evolved Node B (eNB) 106 and other eNBs 108.The eNB 106 provides user and control planes protocol terminationstoward the UE 102. The eNB 106 may be connected to the other eNBs 108via a backhaul (e.g., an X2 interface). The eNB 106 may also be referredto as a base station, a base transceiver station, to radio base station,a radio transceiver, a transceiver function, a basic service set (BSS),an extended service set (ESS), or some other suitable terminology. TheeNB 106 provides an access point to the EPC 110 for a UE 102. Examplesof UEs 102 include a cellular phone, a smart phone, a session initiationprotocol (SIP) phone, a laptop, a personal digital assistant (PDA), asatellite radio, a global positioning system, a multimedia device, avideo device, a digital audio player (e.g., MP3 player), a camera, agame console, a tablet, or any other similar functioning device. The UE102 may also be referred to by those skilled in the art as a mobilestation, a subscriber station, a mobile unit, a subscriber unit, awireless unit, a remote unit, a mobile device, a wireless device, awireless communications device, a remote device, a mobile subscriberstation, an access terminal, a mobile terminal, a wireless terminal, aremote terminal, a handset, a user agent, a mobile client, a client, orsome other suitable terminology.

The eNB 106 is connected to the EPC 110 (e.g., by an S1 interface). TheEPC 110 includes a Mobility Management Entity (MME) 112, other MMEs 114,a Serving Gateway 116, and a Packet Data Network (PDN) Gateway 118. TheMME 112 is the control node that processes the signaling between the UE102 and the EPC 110. Generally, the MME 112 provides bearer andconnection management. All user IP packets are transferred through theServing Gateway 116, which itself is connected to the PDN Gateway 118.The PDN Gateway 118 provides UE IP address allocation as well as otherfunctions. The PDN Gateway 118 is connected to the Operator's IPServices 122. The Operator's IP Services 122 may include the Internet,an intranet, an IP Multimedia Subsystem (IMS), and a Packet-SwitchedStreaming Service (PSS).

FIG. 2 is a diagram illustrating an example of an access network 200 inan LTE network architecture. In this example, the access network 200 isdivided into a number of cellular regions (cells) 202. One or more lowerpower class eNBs 208 may have cellular regions 210 that overlap with oneor more of the cells 202. The lower power class eNB 208 may be a femtocell (e.g., home eNB (HeNB)), pico cell, micro cell, or remote radiohead (RRH). The macro eNBs 204 are each assigned to a respective cell202 and are configured to provide an access point to the EPC 110 for allthe UEs 206 in the cells 202. There is no centralized controller in thisexample of an access network 200, but a centralized controller may beused in alternative configurations. The eNBs 204 are responsible for allradio related functions including radio hearer control, admissioncontrol, mobility control, scheduling, security, and connectivity to theserving gateway 116.

The modulation and multiple access scheme employed by the access network200 may vary depending on the particular telecommunications standardbeing deployed. In LTE applications, OFDM is used on the DL and SC-FDMAis used on the UL to support both frequency division duplexing (FDD) andtime division duplexing (TDD). As those skilled in the art will readilyappreciate from the detailed description to follow, the various conceptspresented herein are well suited for LTE applications. However, theseconcepts may be readily extended to other telecommunication standardsemploying other modulation and multiple access techniques. By way ofexample, these concepts may be extended to Evolution-Data Optimized(EV-DO) or Ultra Mobile Broadband (UMB). EV-DO and UMB are air interfacestandards promulgated by the 3rd Generation Partnership Project 2(3GPP2) as part of the CDMA2000 family of standards and employs CDMA toprovide broadband Internet access to mobile stations. These concepts mayalso be extended to Universal Terrestrial Radio Access (UTRA) employingWideband-CDMA (W-CDMA) and other variants of CDMA, such as TD-SCDMA;Global System for Mobile Communications (GSM) employing TDMA; andEvolved UTRA (E-UTRA), IEEE 802.11 (Wi-Fi), IEEE 802.16 (WiMAX), IEEE802.20, and Flash-OFDM employing OFDMA. UTRA, E-UTRA, UMTS, LTE and GSMare described in documents from the 3GPP organization. CDMA2000 and UMBare described in documents from the 3GPP2 organization. The actualwireless communication standard and the multiple access technologyemployed will depend on the specific application and the overall designconstraints imposed on the system.

The eNBs 204 may have multiple antennas supporting MIMO technology. Theuse of MIMO technology enables the eNBs 204 to exploit the spatialdomain to support spatial multiplexing, beamforming, and transmitdiversity. Spatial multiplexing may be used to transmit differentstreams of data simultaneously on the same frequency. The data steamsmay be transmitted to a single UE 206 to increase the data rate or tomultiple UEs 206 to increase the overall system capacity. This isachieved by spatially precoding each data stream (i.e., applying ascaling of an amplitude and a phase) and then transmitting eachspatially precoded stream through multiple transmit antennas on the DL.The spatially precoded data streams arrive at the UE(s) 206 withdifferent spatial signatures, which enables each of the UE(s) 206 torecover the one or more data streams destined for that UE 206. On theUL, each UE 206 transmits a spatially precoded data stream, whichenables the eNB 204 to identify the source of each spatially precededdata stream.

Spatial multiplexing is generally used when channel conditions are good.When channel conditions are less favorable, beamforming may be used tofocus the transmission energy in one or more directions. This may beachieved by spatially precoding the data for transmission throughmultiple antennas. To achieve good coverage at the edges of the cell, asingle stream beamforming transmission may be used in combination withtransmit diversity.

In the detailed description that follows, various aspects of an accessnetwork will be described with reference to a MIMO system supportingOFDM on the DL. OFDM is a spread-spectrum technique that modulates dataover a number of subcarriers within an OFDM symbol. The subcarriers arespaced apart at precise frequencies. The spacing provides“orthogonality” that enables a receiver to recover the data from thesubcarriers. In the time domain, a guard interval (e.g., cyclic prefix)may be added to each OFDM symbol to combat inter-OFDM-symbolinterference. The UL may use SSC-TDMA in the form of a DFT-spread OFDMsignal to compensate for high peak-to-average power ratio (PAPR).

FIG. 3 is a diagram 300 illustrating an example of a DL frame structurein LTE. A frame (10 ms) may be divided into 10 equally sized sub-frames.Each sub-frame may include two consecutive time slots. A resource gridmay be used to represent two time slots, each time slot including aresource block. The resource grid is divided into multiple resourceelements. In LTE, a resource block contains 12 consecutive subcarriersin the frequency domain and, for a normal cyclic prefix in each OFDMsymbol, 7 consecutive OFDM symbols in the time domain, for a total of 84resource elements. For an extended cyclic prefix, a resource blockcontains 6 consecutive OFDM symbols in the time domain and has a totalof 72 resource elements. Some of the resource elements, indicated as R302, 304, include DL reference signals (DL-RS). The DL-RS includeCell-specific RS (CRS) (also sometimes called common RS) 302 andUE-specific RS (UE-RS) 304. UE-RS 304 are transmitted only on theresource blocks upon which the corresponding physical DL shared channel(PDSCH) is mapped. The number of bits carried by each resource elementdepends on the modulation scheme. Thus, the more resource blocks that aUE receives and the higher the modulation scheme, the higher the datarate for the UE.

FIG. 4 is a diagram 400 illustrating an example of an UL frame structurein LTE. The available resource blocks for the UL may be partitioned intoa data section and a control section. The control section may be formedat the two edges of the system bandwidth and may have a configurablesize. The resource blocks in the control section may be assigned to UEsfor transmission of control information. The data section may includeall resource blocks not included in the control section. The UL framestructure results in the data section including contiguous subcarriers,which may allow a single UE to be assigned all of the contiguoussubcarriers in the data section.

A UE may be assigned resource blocks 410 a, 410 b in the control sectionto transmit control information to an eNB. The UE may also be assignedresource blocks 420 a, 420 b in the data section to transmit data to theeNB. The UE may transmit control information in a physical UL controlchannel (PUCCH) on the assigned resource blocks in the control section.The UL may transmit only data or both data and control information in aphysical UL shared channel (PUSCH) on the assigned resource blocks inthe data section. A UL transmission may span both slots of a subframeand may hop across frequency.

A set of resource blocks may be used to perform initial system accessand achieve UL synchronization in a physical random access channel(PRACH) 430. The PRACH 430 carries a random sequence and cannot carryany UL data/signaling. Each random access preamble occupies a bandwidthcorresponding to six consecutive resource blocks. The starting frequencyis specified by the network. That is, the transmission of the randomaccess preamble is restricted to certain time and frequency resources.There is no frequency hopping for the PRACH. The PRACH attempt iscarried in a single subframe (1 ms) or in a sequence of few contiguoussubframes and a UE can make only a single PRACH attempt per frame (10ms).

FIG. 5 is a diagram 500 illustrating an example of a radio protocolarchitecture for the user and control planes in LTE. The radio protocolarchitecture for the UE and the eNB is shown with three layers: Layer 1,Layer 2, and Layer 3. Layer 1 (L1 layer) is the lowest layer andimplements various physical layer signal processing functions. The L1layer will be referred to herein as the physical layer 506. Layer 2 (L2layer) 508 is above the physical layer 506 and is responsible for thelink between the UE and eNB over the physical layer 506.

In the user plane, the L2 layer 508 includes a media access control(MAC) sublayer 510, a radio link control (RLC) sublayer 512, and apacket data convergence protocol (PDCP) 514 sublayer, which areterminated at the eNB on the network side. Although not shown, the UEmay have several upper layers above the L2 layer 508 including a networklayer (e.g., IP layer) that is terminated at the PDN gateway 118 on thenetwork side, and an application layer that is terminated at the otherend of the connection (e.g., far end UE, server, etc.).

The PDCP sublayer 514 provides multiplexing between different radiobearers and logical channels. The PDCP sublayer 514 also provides headercompression for upper layer data packets to reduce radio transmissionoverhead, security by ciphering the data packets, and handover supportfor LIB between eNBs. The RLC sublayer 512 provides segmentation andreassembly of upper layer data packets, retransmission of lost datapackets, and reordering of data packets to compensate for out-of-orderreception due to hybrid automatic repeat request (HARQ). The MACsublayer 510 provides multiplexing between logical and transportchannels. The MAC sublayer 510 is also responsible for allocating thevarious radio resources (e.g., resource blocks) in one cell among theUEs. The MAC sublayer 510 is also responsible for HARQ operations.

In the control plane, the radio protocol architecture for the UE and eNBis substantially the same for the physical layer 506 and the L2 layer508 with the exception that there is no header compression function forthe control plane. The control plane also includes a radio resourcecontrol (RRC) sublayer 516 in Layer 3 (L3 layer). The RRC sublayer 516is responsible for obtaining radio resources (i.e., radio bearers) andfor configuring the lower layers using RRC signaling between the eNB andthe UE.

FIG. 6 is a block diagram of an eNB 610 in communication with a UE 650in an access network. In the DL, upper layer packets from the corenetwork are provided to a controller/processor 675. Thecontroller/processor 675 implements the functionality of the L2 layer.In the controller/processor 675 provides header compression, ciphering,packet segmentation and reordering, multiplexing between logical andtransport channels, and radio resource allocations to the UE 650 basedon various priority metrics. The controller/processor 675 is alsoresponsible for HARQ operations, retransmission of lost packets, andsignaling to the UE 650.

The transmit (TX) processor 616 implements various signal processingfunctions for the L1 layer (i.e., physical layer). The signal processingfunctions include coding and interleaving to facilitate forward errorcorrection (FEC) at the UE 650 and mapping to signal constellationsbased on various modulation schemes (e.g., binary phase-shift keying(BPSK), quadrature phase-shift keying (QPSK), M-phase-shift keying(M-PSK), M-quadrature amplitude modulation (M-QAM)). The coded andmodulated symbols are then split into parallel streams. Each stream isthen mapped to an OFDM subcarrier, multiplexed with a reference signal(e.g., pilot) in the time and/or frequency domain, and then combinedtogether using an Inverse Fast Fourier Transform (IFFT) to produce aphysical channel carrying a time domain OFDM symbol stream. The OFDMstream is spatially precoded to produce multiple spatial streams.Channel estimates from a channel estimator 674 may be used to determinethe coding and modulation scheme, as well as for spatial processing. Thechannel estimate may be derived from a reference signal and/or channelcondition feedback transmitted by the UE 650. Each spatial stream isthen provided to a different antenna 620 via a separate transmitter618TX. Each transmitter 618TX modulates an RF carrier with a respectivespatial stream for transmission.

At the UE 650, each receiver 654RX receives a signal through itsrespective antenna 652. Each receiver 654RX recovers informationmodulated onto an RF carrier and provides the information to the receive(RX) processor 656. The RX processor 656 implements various signalprocessing functions of the L1 layer. The RX processor 656 performsspatial processing on the information to recover any spatial streamsdestined for the UE 650. If multiple spatial streams are destined forthe UE 650, they may be combined by the RX processor 656 into a singleOFDM symbol stream. The RX processor 656 then converts the OFDM symbolstream from the time-domain to the frequency domain using a Fast FourierTransform (FFT). The frequency domain signal comprises a separate OFDMsymbol stream for each subcarrier of the OFDM signal. The symbols oneach subcarrier, and the reference signal, are recovered and demodulatedby determining the most likely signal constellation points transmittedby the eNB 610. These soft decisions may be based on channel estimatescomputed by the channel estimator 658. The soft decisions are thendecoded and deinterleaved to recover the data and control signals thatwere originally transmitted by the eNB 610 on the physical channel. Thedata and control signals are then provided to the controller/processor659.

The controller/processor 659 implements the L2 layer. Thecontroller/processor can be associated with a memory 660 that storesprogram codes and data. The memory 660 may be referred to as acomputer-readable medium. In the UL, the controller/processor 659provides demultiplexing between transport and logical channels, packetreassembly, deciphering, header decompression, control signal processingto recover upper layer packets from the core network. The upper layerpackets are then provided to a data sink 662, which represents all theprotocol layers above the L2 layer. Various control signals may also beprovided to the data sink 662 for L3 processing. Thecontroller/processor 659 is also responsible for error detection usingan acknowledgement (ACK) and/or negative acknowledgement (NACK) protocolto support HARQ operations.

In the UL, a data source 667 is used to provide upper layer packets tothe controller/processor 659. The data source 667 represents allprotocol layers above the L2 layer. Similar to the functionalitydescribed in connection with the DL transmission by the eNB 610, thecontroller/processor 659 implements the L2 layer for the user plane andthe control plane by providing header compression, ciphering, packetsegmentation and reordering, and multiplexing between logical andtransport channels based on radio resource allocations by the eNB 610.The controller/processor 659 is also responsible for HARQ operations,retransmission of lost packets, and signaling to the eNB 610.

Channel estimates derived by a channel estimator 658 from a referencesignal or feedback transmitted by the eNB 610 may be used by the TXprocessor 668 to select the appropriate coding and modulation schemes,and to facilitate spatial processing. The spatial streams generated bythe TX processor 668 are provided to different antenna 652 via separatetransmitters 654TX. Each transmitter 654TX modulates an RF carrier witha respective spatial stream for transmission.

The UL transmission is processed at the eNB 610 in a manner similar tothat described in connection with the receiver function at the UE 650.Each receiver 618RX receives a signal through its respective antenna620. Each receiver 618RX recovers information modulated onto an RFcarrier and provides the information to a RX processor 670, The RXprocessor 670 may implement the L1 layer.

The controller/processor 675 implements the L2 layer. Thecontroller/processor 675 can be associated with a memory 676 that storesprogram codes and data. The memory 676 may be referred to as acomputer-readable medium. In the UL, the control/processor 675 providesdemultiplexing between transport and logical channels, packetreassembly, deciphering, header decompression, control signal processingto recover upper layer packets from the UE 650. Upper layer packets fromthe controller/processor 675 may be provided to the core network. Thecontroller/processor 675 is also responsible for error detection usingan ACK and/or NACK protocol to support HARQ operations.

FIG. 7 is a diagram 700 illustrating a range expanded cellular region ina heterogeneous network, A lower power class eNB such as the RRH 710 bmay have a range expanded cellular region 703 that is expanded from thecellular region 702 through enhanced inter-cell interferencecoordination between the RRH 710 b and the macro eNB 710 a and throughinterference cancelation performed by the UE 720. In enhanced inter-cellinterference coordination, the RRH 710 b receives information from themacro eNB 710 a regarding an interference condition of the UE 720. Theinformation allows the RRH 710 b to serve the UE 720 in the rangeexpanded cellular region 703 and to accept a handoff of the UE 720 fromthe macro eNB 710 a as the UE 720 enters the range expanded cellularregion 703.

Coordinated multipoint (CoMP) enables the dynamic coordination oftransmission and reception using a plurality of different base stations.CoMP transmission schemes typically enable multiple, base stations tocoordinate transmissions to one or more tJEs CoMP) and/or receptionsfrom one or more UEs (UL CoMP). DL CoMP and UL CoMP can be separately orjointly enabled for a UE. In one example, joint transmission DL CoMPuses multiple eNBs to transmit the same data to a UE In another example,joint reception UT. CoMP uses multiple eNBs that receive the same datafrom a UE. In another example, coordinated beamforming (CBF) involvestransmitting from an eNB to a UE using beams that are chosen to reduceinterference to UEs in neighboring cells. In another example, dynamicpoint selection (DPS) enables the cell or cells involved in datatransmissions to change from subframe to subframe.

CoMP may be implemented in homogeneous networks and/or heterogeneousnetworks (HetNet), Multiple eNBs may cooperate to determine scheduling,transmission parameters, and transmit antenna weights for a UE. Nodesinvolved in CoMP can be connected using an X2 interface, which may becharacterized by some latency and limited bandwidth, and/or by fiber tominimize latency and obtain greater bandwidth that is effectively“unlimited bandwidth.” In HetNet CoMP, a low power node may be referredto as an RRH.

Two reference signals that are transmitted from the same or fromdifferent cells can be said to be quasi-co-located (QCL) if they have atleast the same frequency shift, Doppler spread, received timing, and/ordelay spread from the UE perspective. CoMP operation may require certainPDSCH resource element (RE) mapping, and QCL of channel stateinformation reference signals (CSI-RS) and user equipment referencesignals (UE-RS) (also known as demodulation reference signals (DMRS)).For RRC signaling, up to four sets of PDSCH RE mapping and QCLparameters per component carrier may be indicated by DCI. In oneexample, DCI signaling may include a new DCI bit that together withnSCID, dynamically selects the PDSCH RE mapping and QCL parameter setamong four parameter sets configured by higher layers. For example, thenew DCI bit may be referred to as a “PDSCH RE Mapping andQuasi-Co-Location Indicator” (PQI) bit. In an aspect, the PQI bit may beadded to the contents of DCI format 2C to form the DCI format 2D fordownlink transmission mode (TM) 10. In another aspect, two PQI bits maybe added to the contents of DCI format 2C to form the DCI format tierdownlink TM 10.

Each of the sets that can be signaled in DCI may correspond to ahigher-layer list of parameters. In an aspect, the higher-layer list ofparameters may include a number of cell-specific reference signal (CRS)ports {1, 2, 4, . . . , x} a CRS frequency shift, an MBSFN subframeconfiguration, a configuration of ZP CSI-RS, a PDSCH starting symbolthat may be a value N={0 or reserved value, 1, 2, 3, 4 (only for systembandwidth<=10 PRBs), a physical control format indicator channel(PCFICH) of a serving cell in case of non-cross-scheduling orhigher-layer configured value in case of cross-carrier scheduling},and/or an NZP CSI-RS resource index, where QCL is assumed between UE-RSand the CSI-RS resource.

A UE can be configured to handle up to five component carriers (CCs) forcarrier aggregation (CA), where one of the component carriers isdesignated as the primary CC (PCC) while the remaining componentcarriers are referred to as secondary CCs (SCC). Cross-carrierscheduling may be supported for a UE with CA, where a PDSCH can bescheduled on an SCC (also referred to as the scheduled CC) by a physicaldownlink control channel (PDCCH) on a different CC (also referred to asthe scheduling CC) which can be a PCC or an SCC. In this case, a 3-bitcross-carrier indicator field (CIF) may be included in the downlinkcontrol information (DCI) for both the scheduling CC and the scheduledCC. The scheduling CC may include UE-specific search space not only foritself, but also for the CCs that are cross-scheduled by the schedulingCC. The two or more UE-specific search spaces for PDSCH transmissions ontwo or more different CCs can be a function of the CIFs configured foreach respective CC, and may be designed to avoid search spaceoverlapping among the two or more CCs to a large extent.

DCI may be carried in a PDCCH. DCI may include transmission resourceassignments and other control information for a UE or group of UEs.PDCCH is located in a first several symbols in a subframe and are fullydistributed across the entire system bandwidth. PDCCH is time divisionmultiplexed with PDSCH. The PDCCH is transmitted in a subframe and thesubframe is effectively divided into a control region and a data region.

Enhanced PDCCH (EPDCCH) can facilitate frequency-domain based inter-cellinterference coordination and the presence of EPDCCH on a carrier may besubframe dependent, such that EPDCCH may not always be present in allsub frames.

In contrast to PDCCH, which occupies the first several control symbolsin a subframe, EPDCCH occupies the data region of the subframe, similarto PDSCH. Certain enhancements may be enabled by EPDCCH, includingincreased control channel capacity, support for frequency-domaininter-cell interference coordination (ICIC), improved spatial reuse ofcontrol channel resources, and support for beamforming and/or diversity.Moreover, EPDCCH may be used in additional new carrier types and in subframes of a multicast-broadcast single frequency network (MBSFN).Typically, EPDCCH can coexist on the same carrier as legacy UEsconfigured to obtain control information from PDCCH.

In certain aspects, both localized and distributed transmission ofEPDCCH is supported. A UE-RS based EPDCCH may be supported. UE-RS mayuse antenna ports 107, 108, 109, and 110, whereas PDSCH utilizes antennaports 7-14.

EPDCCH is based on frequency division multiplexing (FDM), spanning boththe first and second slots of a subframe. A restriction may be placed onthe maximum number of transport channel (TrCH) bits receivable in atransmission time interval (TTI) such that a relaxation of theprocessing requirements for the UE can be achieved. For example, therestriction on the maximum number of TrCH bits receivable in a TTI maydepend on UE capability or whether a condition is satisfied (e.g., whena round trip time (RTT)>100 us). Multiplexing of PDSCH and EPDCCH withina physical resource block (PRB) pair may not be permitted, in oneexample, a PRB may be configured as a unit of transmission resourceincluding 12 sub-carriers in the frequency domain and 1 timeslot (0.5ms) in the time domain.

An RE that collides with any other signal is typically not used forEPDCCH. Coding chain rate-matching may be used for CRS, and for newantenna ports on a new carrier type (NCT). Coding chain rate-matchingmay be also used for a legacy control region (a region up to the PDSCHstarting position) for physical broadcast channel (PBCH) and PSS and/orsecondary synchronization signals (SSS) when EPDCCH transmission inthese PRB pairs is supported. Coding chain rate-matching may be alsoused around zero power (ZP) and non-zero power (NZP) CSI-RS configuredfor the UE receiving the EPDCCH.

In subframes where a UE monitors EPDCCH UE search space (USS) on a firstcarrier, the UE typically does not monitor PDCCH USS on the samecarrier. A configuration may define whether localized or distributedEPDCCH candidates are monitored in a particular subframe. The UE alsotypically monitors the common search space (CSS) on PDCCH.Alternatively, the UE may monitor the CSS on ePDCCH, if CSS on ePDCCH issupported in the subframe, e.g., in a new carrier type. The UE can beconfigured to monitor both localized and distributed EPDCCH candidatesin a subframe. If the UE is configured to monitor both localized anddistributed EPDCCH candidates in a subframe, the total number of USSblind decodes on the carrier may not be increased.

The subframes in which EPDCCH USS is monitored by the UE may bepredefined by networking standards. In one example, in special subframeswith a configuration of 0 and 5 for normal cyclic prefix (CP), and 0 and4 for extended CP, EPDCCH may not be monitored by the UE. Monitoredsubframes can also be configured by higher layer signaling. In subframesnot configured for monitoring EPDCCH, the UE may monitor CSS and/or USSon PDCCH.

A UE can be configured with K EPDCCH resource sets (where K≧1), e.g., upto two sets. An EPDCCH resource set may be defined as a group of N PRBpairs, and each EPDCCH resource set may define its own size (e.g., 2, 4or 8 PRB pairs). The total number of blind decoding attempts isindependent from K, and the total blind decoding attempts for a UE maybe split into configured K EPDCCH resource sets. Each EPDCCH resourceset may be configured for either localized EPDCCH or distributed EPDCCH,PRB pairs of EPDCCH resource sets with different logical EPDCCH setindices can be fully overlapped, partially overlapped, or may benon-overlapping.

The same scrambling sequence generator defined for a PDSCH UE-RS can beused for EPDCCH UE-RS. In one example, the scrambling sequence generatorof UE-RS for EPDCCH on ports 107 through 110 is initialized by:c _(init)=(└n _(s)/2┘+1)·(2X+1)·2¹⁶ +n _(SCID)where c_(init) represents an initialization value, n_(s) represents aslot number within a radio frame, X represents a candidate value, andn_(SCID) represents a scrambling identifier. For example, X may beconfigured by UE-specific higher layer signaling, one value per set, andthe default value of X for the second set may be the same as the valuefor the first set.

A starting symbol may be preconfigured for EPDCCH. The starting symbolmay be configured by per-cell, higher layer signaling, which may betransmitted to indicate the OFDM starting symbol for any EPDCCH sent ona cell and PDSCH on that cell may be scheduled by EPDCCH. If thestarting symbol is not provided, the starting OFDM symbol of EPDCCH andPDSCH scheduled by EPDCCH is typically derived from PCFICH. A singlevalue of OFDM starting symbol may be applicable to both EPDCCH resourcesets, when two sets are configured. Alternatively, the OFDM startingsymbol may be separately configured for each of the K EPDCCH resourcesets.

QCL may be used with EPDCCH. A UE may be configured by higher layersignaling and a QCL-CSI-RS-Index can be transmitted to indicate thequasi-collocation assumption as EPDCCH UE-RS. The QCL-CSI-RS-Index maybe configured per EPDCCH resource set. When signaling is provided,EPDCCH UE-RS ports typically may not be assumed as quasi co-located withany RS port, with the exception that all EPDCCH UE-RS ports within theEPDCCH resource set may be assumed as quasi co-located with the CSI-RSresource indicated by QCL-CSI-RS-Index with respect to delay spread,doppler spread, doppler shift, and/or average delay. It should be notedthat the QCL-CSI-RS-Index corresponds to a non-zero power CSI-RSresource from a CoMP measurement set.

When signaling is not provided, all EPDCCH UE-RS ports may be assumed tobe quasi co-located with CRS for the serving cell with respect to delayspread, doppler spread, doppler shift, and/or average delay.

EPDCCH is transmitted using resources in units of enhanced controlchannel elements (ECCEs). ECCE may be formed by a number N enhancedresource element groups (EREGs) in distributed and localizedtransmission. As an example, in a normal subframe (with normal CP) orspecial subframe configurations 3, 4, 8 (with normal CP), each EREG mayconsist of 9 resource elements (REs) in a PRB pair. In an aspect, eachECCE may be configured to include 4 EREGs N=4) or 36 REs. For example,if each PRB pair consist of 144 REs, which is 16 EREGs, each PRB pairmay consist of four ECCEs (e.g., 16 EREGs) that can be available forlocalized or distributed transmission(s). In special subframeconfigurations 1, 2, 6, 7, 9 (with normal CP), a normal subframe (withextended CP), and special subframe configurations 1, 2, 3, 5, 6 (withextended CP), N may be set to 8. In this example, two ECCEs (each of 8EREGs) per PRB pair may be available for localized transmission(s).

In normal subframes (with normal CP) or special subframe configurations3, 4, 8 (with normal CP), and where the available REs in a PRB pair isless than X_(thresh), the aggregation levels supported for EPDCCHinclude 2, 4, 8, 16 for localized EPDCCH and 2, 4, 8, 16, 32 fordistributed EPDCCH, where an aggregation level of L consists of L ECCEs.In all other cases, the supported aggregation levels include 1, 2, 4,and 8 for localized EPDCCH and 1, 2, 4, 8 and 16 for distributed EPDCCH.

Aggregation levels supported for EPDCCH when X_(thresh)=104: the numberof available REs used to compare to X_(thresh) is counted from the UEperspective by considering the UE-specific CSI-RS configuration, but notthe CSI-RS configurations for other UEs. The total number of EPDCCH USSblind decodes per CC is typically 32 or 48 depending on theconfiguration of UL MIMO.

In some aspects, one or more EPDCCH parameters may be configured tocorrespond to same or similar parameters defined for PDSCH. Suchparameters may include starting symbol, rate-matching and/or QCLindication parameters. A predefined rule or RRC configuration canspecify the linkage between EPDCCH and PDSCH sets. In one example, up tofour sets of starting symbol, rate-matching and QCL states may beconfigured for PDSCH and up to two sets of starting symbol,rate-matching and QCL states can be defined for EPDCCH. In such example,one of the two sets may be defined for a first EPDCCH resource set andthe other of the two sets may be defined for a second EPDCCH resourceset. For example, a predefined rule may require that a first EPDCCHresource set assumes the values of a first set of parameters configuredfor PDSCH, and a second EPDCCH resource set assumes the values of asecond set of parameters configured for PDSCH. The EPDCCH resource setsmay define values for starting symbol, rate-matching and QCL operationfor EPDCCH.

In some aspects, a UE, may be configured to perform rake-matching basedon one or more of CSI-RS and CRS for EPDCCH. For example, a UE may beconfigured to always rate-match around all CSI-RS configurations definedfor the UE. In such aspects, there is typically no EPDCCH resourceset-dependency, and no selective CSI-RS rate matching.

In some aspects, a UE may be configured to perform selective and/orset-dependent CSI-RS rate-matching. In such aspects, the number ofavailable REs for EPDCCH in a PRB pair may be set-dependent. Forexample, when the number of available REs in each of two EPDCCH resourcesets are compared with X_(thresh), one EPDCCH resource set may have oneaggregation level set (e.g., aggregation level set {1, 2, 4, 8}) and theother EPDCCH resource set may have a different aggregation level set(e.g., aggregation level set {2, 4, 8, 16}).

For CSI-RS, the determination of aggregation level (e.g., comparing. REavailability with X_(thresh)) may be EPDCCH resource set independent orEPDCCH resource set-dependent. Rate-matching around CSI-RS in an EPDCCHcoding chain can be EPDCCH resource set independent or EPDCCH resourceset-dependent. For example, a UE may determine the aggregation level byassuming that all CSI-RS configured for a UE are excluded. However, a UEmay determine rate-matching by excluding only a subset of CSI-RSconfigured for the UE. In some embodiments, the same CSI-RS selectivitymay be employed for both aggregation level determination andrate-matching around CSI-RS in a coding chain for a given EPDCCHresource set.

In some aspects, selective and/or set-dependent CRS rate-matching can bedefined. The CRS used may be the CRS of a serving cell, or one or moreneighboring cells. The CRS configuration can be different for differentcells. In one example, the CRS configuration may be defined as a numberof ports and a frequency shift, for bath MBSFN subframes and non-MBSFNsubframes. In some embodiments, set-dependency and subframe-dependency(MBSFN vs. non-MBSFN) can be applied.

In one example, a UE is configured with CSI-RS indices (e.g., indices 1,2, 3, 4, 5, 6, 7) for both PDSCH and ePDCCH. Of the CSI-RS indices, asubset (e.g., indices 1, 2, 3, 4) may be assigned to NZP CSI-RS, andanother subset (e.g., indices 5, 6, 7) may be assigned to ZP CSI-RS.Each of the CSI-RS indices may be separately associated with a certainnumber of CSI-RS ports and REs. Furthermore, there may be two EPDCCHresource sets, which may correspond for example to different eNBs. Thetwo EPDCCH resource sets may have associated CSI-RS indices of (1) forEPDCCH resource set 1, and (2,3) for EPDCCH resource set 2.

In some aspects, the total number of combined rate matching and QCLstates across the PDSCH and PDCCH does not exceed four. It should beunderstood that various embodiments of the invention may employdifferent techniques to determine which resources are usable and to ratematch around resources assigned to or used for CSI-RS.

In an aspect, a non-selective and set-independent approach may beemployed for determining usable resources for EPDCCH and forrate-matching around CSI-RS, where all CSI-RS indices are considered.For example, the total of CSI-RS indices (e.g., indices 1, 2, 3, 4, 5,6, 7), whether usable or not, may be assumed to be allocated and/orunusable in order to determine which resources are usable for EPDCCH andfor rate-matching around CSI-RS.

In an aspect, a selective and set-independent approach may be employedfor determining usable resources for EPDCCH and for rate-matching aroundCSI-RS, where a common set of CSI-RS indices is considered. For example,the common set may be a subset of all the CSI-RS indices (e.g., a subsetincluding indices 1, 2, 3) which are configured for CSI-RS in one orother EPDCCH sets and should then be considered in determining EPDCCHfor both usable resource determination and rate match around.

In an aspect, a selective and partial set-dependent approach may beemployed for determining usable resources for EPDCCH and forrate-matching around CSI-RS, where a common set of CSI-RS indices isconsidered. In such aspect, however, rate-matching may be set specific.For example, the available number of resources may be determined usingCSI-RS indices (e.g., indices 1, 2, 3) configured for CSI-RS for EPDCCH.The available number of resources may then be compared with X_(thresh)to determine a set of aggregation levels. The determined set ofaggregation levels may be considered as a common set of aggregationlevels that may be applied to both EPDCCH resource sets. However, CSI-RSindices (1) may be used for rate matching in EPDCCH set 1, and CSI-RSindices (2,3) may be used for rate matching in EPDCCH set 2.

In certain aspects, one or more rules may be applied in differentscenarios when determining the common number of usable REs. For example,the one or more rules may include a rule to use total resources of NZPCSI-RS, e.g. (indices 1, 2, 3, 4), a rule to use total resources ofCSI-RS for ePDCCH, e.g. (indices 1, 2, 3), a rule to use minimum of thetwo set, e.g. (index 1), and/or a rule to use maximum of the two sets,e.g. (indices 2, 3).

As also discussed herein, certain embodiments employ other approachesand apply different rules. For example, a selective and set-dependentapproach may be employed whereby both usable resource determination andrate-matching are selective and set-dependent. It should be understoodthat the previously discussed principles and approaches can be appliedfor dealing with CRS and other signals.

In an aspect, for the case of PDSCR, a UE may be configured to ratematch around all configured NZP CSI-RS resources while allowing forset-dependent ZP CSI-RS rate matching definitions. In such aspect, thesame definitions may be applied for the EPDCCH.

In an aspect, when an EPDCCH starting symbol in a subframe is zero, a UEmay monitor and decode legacy control in the subframe or refrain frommonitoring and decoding the legacy control in the subframe. Legacycontrol may include PCFICH, PHICH, and a common search space. In anotheraspect, the UE may be configured to skip decoding in some EPDCCHsubframes. The UE may skip decoding of all legacy control, or only asubset of legacy control. For example, the UE may decode PCFICH, butskip decoding PHICH and the common search space. By decoding channels,such as PCFICH, the UE may be able to determine starting symbol forPDSCH based on the PCFICH.

In one example, the UE may be configured to skip decoding EPDCCHsubframes that do not carry DL broadcast transmissions, such as MBSFNsubframes used for unicast. In another example, the UE may be configuredto skip decoding EPDCCH subframes when the starting symbol for EPDCCHfor two or more EPDCCH resource sets is zero.

When EPDCCH symbols are mapped to the first symbol in an EPDCCHsubframe, rate-matching operations may completely ignore the controlregion. For example, the rate-matching operations may completely ignorethe control region when the UE attempts to decode legacy control. Insome embodiments, ePDCCH symbols may be mapped only to the tones in thefirst symbol that do not contain at least some legacy control, such astones that carry PCFICH.

FIG. 8 includes a flow chart 800 of a method of wireless communication.The method may be performed by a UE, such as UE 720. At step 802, the UEreceives a first set of configurations for a PDSCH, each configurationin the first set of configurations defining at least one of a startingsymbol, rate-matching information, or a QCL indication. In an aspect,the first set of configurations includes four PDSCH configurations. Inan aspect, the PDSCH is implemented in a coordinated multipoint system.

At step 804, the UE receives a second set of configurations for anEPDCCH, the second set of configurations being a subset from among thefirst set of configurations. In an aspect, the EPDCCH may be included ina first resource set and a second resource set, and the second set ofconfigurations includes a first EPDCCH configuration and a second EPDCCHconfiguration. In such aspect, the first EPDCCH configuration may bedefined for processing the EPDCCH on the first resource set and thesecond EPDCCH configuration may be defined for processing the EPDCCH onthe second resource set. In an aspect, the second set of configurationsincludes two EPDCCH configurations that are a subset from among the fourPDSCH configurations. For example, for a given serving cell, if the UEis configured via higher layer signaling to receive PDSCH datatransmissions according to transmission mode 10, and if the UE, isconfigured to monitor EPDCCH, for each EPDCCH-PRB-set, the UE may usethe parameter set indicated by a the higher layer parameter (e.g.,re-MappingQCLConfigListId-r11) for determining the EPDCCH RE mapping andEPDCCH antenna port quasi co-location. In an aspect, the second set ofconfigurations is selected from the first of configurations based on anRRC configuration

At step 806, the UE receives the EPDCCH. In an aspect, EPDCCH isreceived on the first resource set and the second resource set.

At step 808, the UE processes the EPDCCH based on at least oneconfiguration from the second set of configurations.

FIG. 9 includes a flow chart 900 of a method of wireless communication.The method may be performed by a UE, such as UE 720. At step 902, the UEdetermines at least a first resource set and a second resource setconfigured for a control channel. In an aspect, the control channel maybe an EPDCCH.

At step 904, the UE determines a common set of aggregation levels forthe first resource set and the second resource set. In an aspect, the UEdetermines the common set of aggregation levels by determining at leasta first number of available resources in the first resource set, asecond number of available resources in the second resource set, orboth. In an aspect, the UE may determine the common set of aggregationlevels by comparing the first number of available resources to athreshold value, the second number of available resources to a thresholdvalue, or both, and selecting the common set of aggregation levels basedon the comparison.

For example, a UE may determine that a first PRB pair (e.g., consistingof 12 tones and 14 symbols in a normal CP configuration) allocated as afirst resource set for EPDCCH includes a total of 168 REs and a secondPRB pair (e.g., consisting of 12 tones and 14 symbols in a normal CPconfiguration) allocated as a second resource set for EPDCCH includes atotal of 168 REs. The UE may further determine that 120 REs of the 168REs are available in the first resource set for EPDCCH and that 80 REsof the 168 REs are available in the second resource set for EPDCCH. TheUE may compare the determined number of available REs in the first andsecond resource sets for EPDCCH to a predetermined threshold valueX_(thresh). For example, X_(thresh) may be set to 104 and the UE may usean aggregation level {1, 2, 4, 8} for monitoring a resource set forEPDCCH if the determined number of available REs in the resource set forEPDCCH is equal to or greater than 104. Otherwise, if the determinednumber of available REs in the resource set for EPDCCH is less than 104,the UE may use an aggregation level {2, 4, 8, 16} for monitoring theresource set for EPDCCH. In an aspect, the UE may select the largestdetermined aggregation level (e.g., aggregation level {2, 4, 8, 16}) asthe common aggregation level for monitoring both the first and secondresource sets for EPDCCH.

At step 906, the UE determines first rate-matching parameters for thefirst resource set and second rate-matching parameters for the secondresource set. In an aspect, the first rate-matching parameters areconfigured to rate-match around all CSI-RS in the first resource set orrate-match around a subset of the CSI-RS in the first resource set. Insuch aspect, the second rate-matching parameters are configured torate-match around all of the CSI-RS on the second resource set orrate-match around a subset of the CSI-RS on the second resource set.

In an aspect, the first rate-matching parameters are configured torate-match around all CRS in the first resource set or rate-match arounda subset of the CRS on the first resource set. In such aspect, thesecond rate-matching parameters are configured to rate-match around allof the CRS on the second resource set or rate-match around a subset ofthe CRS in the second resource set. In an aspect, the firstrate-matching parameters are determined based on a first RRCconfiguration and the second rate-matching parameters are determinedbased on a second RRC configuration.

At step 908, the UE processes the control channel using at least thecommon set of aggregation levels and the first rate-matching parametersand second rate-matching parameters.

FIG. 10 includes a flow chart 1000 of a method of wirelesscommunication. The method may be performed by UE. At step 1002, the UEreceives a DL signal that includes at least one or more controlchannels. In an aspect, the control channel may be an EPDCCH.

At step 1004, the UE determines whether a starting symbol of an EPDCCHis an initial symbol in a subframe based on an EPDCCH configuration.

At step 1006, the UE refrains from decoding a subset of legacy controlchannels in the subframe when the starting symbol of the EPDCCH is theinitial symbol in the subframe. In an aspect, the legacy controlchannels include at least one of a PCFICH, a PHICH or a combinationthereof. In an aspect, the UE refrains from decoding a subset of legacycontrol channels by refraining from decoding the subset of legacycontrol channels in the subframe when the subframe does not include a DLbroadcast transmission.

In an aspect, the EPDCCH configuration may identify a first EPDCCHresource set and a second EPDCCH resource set. In such aspect, the UErefrains from decoding a subset of legacy control channels by refrainingfrom decoding the subset of legacy control channels in the subframe whenboth a starting symbol of the first EPDCCH resource set and a startingsymbol of the second EPDCCH resource set are the initial symbol in thesubframe.

FIG. 11 includes a flow chart 1100 of a method of wirelesscommunication. The method may be performed by a UE, such as UE 720. Atstep 1102, the UE receives downlink control information including setsof parameters defining EPDCCH resource element mapping andquasi-co-location parameters related to two or more transmitters in acoordinated multipoint system.

At step 1104, the UE performs rate-matching around CSI-RS or CRS at areceiver using on one or more of the plurality of the sets ofparameters. In some embodiments, the rate-matching is performed aroundthe CSI-RS using a set of parameters that is selected based on anaggregation level associated with the selected set of parameters. Eachset of parameters may define one or more of a configuration of CSI-RS, aPDSCH starting symbol, PCFICH of a serving cell, and a NZP CSI-RSresource index.

In some embodiments, the rate-matching is performed around the CRS usinga set of parameters that is selected based on an aggregation levelassociated with the selected set of parameters. Each set of parametersmay define one or more of a number of a CRS port, a CRS frequency shift,and a MBSFN subframe configuration. The CRS may relate to a servingcell.

In some embodiments, the UE determines whether a starting symbol ofEPDCCHs is a zero symbol (also referred to as the “initial symbol”),decoding control information in the EPDCCHs when the starting symbol isnot the zero symbol, and refraining from decoding control information inat least some of the EPDCCHs when the starting symbol is the zerosymbol.

FIG. 12 is a conceptual data flow diagram 1200 illustrating the dataflow between different modules/means/components in an exemplaryapparatus 1202. The apparatus may be a UE. The apparatus includes amodule 1204 that receives a DL signal that includes at least one or morecontrol channels, receives a first set of configurations for a PDSCH,each configuration in the first set of configurations defining at leastone of a starting symbol, rate-matching information, or a QCLindication, receives a second set of configurations for an EPDCCH, thesecond set of configurations being a subset from among the first set ofconfigurations, and/or receives the EPDCCH.

The apparatus further includes a module 1206 that determines at least afirst resource set and a second resource set configured for a controlchannel, determines a common set of aggregation levels for the firstresource set and the second resource set, determines first rate-matchingparameters for the first resource set and second rate-matchingparameters for the second resource set, and/or determines whether astarting symbol of an EPDCCH is an initial symbol in a subframe.

The apparatus further includes a module 1208 that processes the EPDCCHbased on at least one configuration from the second set ofconfigurations and/or processes the control channel using at least thecommon set of aggregation levels and the first rate-matching parametersand second rate-matching parameters.

The apparatus further includes a module 1210 that refrains from decodinga subset of legacy control channels in the subframe when the startingsymbol of the EPDCCH is the initial symbol in the subframe, and a module1212 that transmits UL transmissions to an eNB (e.g., eNB 1250).

The apparatus may include additional modules that perform each of thesteps of the algorithm in the aforementioned flow charts of FIGS. 8-11.As such, each step in the aforementioned flow charts of FIGS. 8-11 maybe performed by a module and the apparatus may include one or more ofthose modules. The modules may be one or more hardware componentsspecifically configured to carry out the stated processes/algorithm,implemented by a processor configured to perform the statedprocesses/algorithm, stored within a computer-readable medium forimplementation by a processor, or some combination thereof.

FIG. 13 is a diagram 1300 illustrating an example of a hardwareimplementation for an apparatus 1202′ employing a processing system1314. The processing system 1314 may be implemented with a busarchitecture, represented generally by the bus 1324. The bus 1324 mayinclude any number of interconnecting buses and bridges depending on thespecific application of the processing system 1314 and the overalldesign constraints. The bus 1324 links together various circuitsincluding one or more processors and/or hardware modules, represented bythe processor 1304, the modules 1204, 1206, 1208, 1210, and 1212, andthe computer-readable medium memory 1306. The bus 1324 may also linkvarious other circuits such as timing sources, peripherals, voltageregulators, and power management circuits, which are well known in theart, and therefore, will not be described any further.

The processing system 1314 may be coupled to a transceiver 1310. Thetransceiver 1310 is coupled to one or more antennas 1320. Thetransceiver 1310 provides a means for communicating with various otherapparatus over a transmission medium. The transceiver 1310 receives asignal from the one or more antennas 1320, extracts information from thereceived signal, and provides the extracted information to theprocessing system 1314, specifically the receiving module 1204. Inaddition, the transceiver 1310 receives information from the processingsystem 1314, specifically the transmission module 1212, and based on thereceived information, generates a signal to be applied to the one ormore antennas 1320. The processing system 1314 includes a processor 1304coupled to a computer-readable medium/memory 1306. The processor 1304 isresponsible for general processing, including the execution of softwarestored on the computer-readable medium/memory 1306. The software, whenexecuted by the processor 1304, causes the processing system 1314 toperform the various functions described supra for any particularapparatus. The computer-readable medium/memory 1306 may also be used forstoring data that is manipulated by the processor 1304 when executingsoftware. The processing system further includes at least one of themodules 1204, 1206, 1208, 1210, and 1212. The modules may be softwaremodules running in the processor 1304, resident/stored in the computerreadable medium/memory 1306, one or more hardware modules coupled to theprocessor 1304, or some combination thereof. The processing system 1314may be a component of the UE 650 and may include the memory 660 and/orat least one of the TX processor 668, the RX processor 656, and thecontroller/processor 659.

In one configuration, the apparatus 1202/1202′ for wirelesscommunication includes means for receiving a first set of configurationsfor a PDSCH, each configuration in the first set of configurationsdefining at least one of a starting symbol, rate-matching information,or a QCL indication, means for receiving a second set of configurationsfor an EPDCCH, the second set of configurations being a subset fromamong the first set of configurations, means for receiving the EPDCCH,means for processing the EPDCCH based on at least one configuration fromthe second set of configurations, means for determining at least a firstresource set and a second resource set configured for a control channel,means for determining a common set of aggregation levels for the firstresource set and second resource set, means for determining firstrate-matching parameters for the first resource set and secondrate-matching parameters for the second resource set, means forprocessing the control channel using at least the common set ofaggregation levels and the first rate-matching parameters and secondrate-matching parameters, means for determining whether a startingsymbol of an EPDCCH is an initial symbol in a subframe, and means forrefraining from decoding a subset of legacy control channels in thesubframe when the starting symbol of the EPDCCH is the initial symbol inthe subframe. The aforementioned means may be one or more of theaforementioned modules of the apparatus 1202 and/or the processingsystem 1314 of the apparatus 1202′ configured to perform the functionsrecited by the aforementioned means. As described supra, the processingsystem 1314 may include the TX Processor 668, the RX Processor 656, andthe controller/processor 659. As such, in one configuration, theaforementioned means may be the TX Processor 668, the RX Processor 656,and the controller/processor 659 configured to perform the functionsrecited by the aforementioned means.

FIG. 14 includes a flow chart 1400 of a method of wirelesscommunication. The method may be performed by an eNB, such as eNB 710 a.At step 1402, the eNB configures a first set of configurations for aPDSCH, each configuration in the first set of configurations defining atleast one of a starting symbol, rate-matching information, or a QCLindication. In an aspect, the first set of configurations includes fourPDSCH configurations. In an aspect, the PDSCH is implemented in acoordinated multipoint system.

At step 1404, the eNB configures a second set of configurations for anEPDCCH, the second set of configurations being a subset from among thefirst set of configurations. As such, the second set of configurationsmay be signaled explicitly, or may be a set of indices identifying asubset of configurations from the first set of configurations.Alternatively, the second set of configuration may always be a subsetmade up of the first N configurations in the first set ofconfigurations, where N is less than the total number of configurationsin the first set of configurations, and where N may be pre-determined,static, or dynamic.

In an aspect, the EPDCCH may be included in a first resource set and asecond resource set, and the second set of configurations includes afirst EPDCCH configuration and a second EPDCCH configuration. In suchaspect, the first EPDCCH configuration may be defined for processing theEPDCCH by a UE on the first resource set and the second EPDCCHconfiguration may be defined for processing the EPDCCH by a UE on thesecond resource set. In an aspect, the second set of configurationsincludes two EPDCCH configurations that are a subset from among the fourPDSCH configurations. In an aspect, the second set of configurations areselected from the first of configurations based on an RRC configuration.

At step 1406, the eNB transmits the first set of configurations for thePDSCH and the second set of configurations for the EPDCCH.

At step 1408, the eNB transmits the EPDCCH. In an aspect, the eNBtransmits the EPDCCH on the first resource set and the second resourceset.

FIG. 15 includes a flow chart 1500 of a method of wirelesscommunication. The method may be performed by an eNB, such as eNB 710 a.At step 1502, the eNB configures at least a first resource set and asecond resource set for a control channel. The first and second resourcesets are configured with a common reference signal configuration. Forexample, the common reference signal configuration may include a commonCSI-RS configuration or a common CRS configuration. In an aspect, thecontrol channel may be an EPDCCH.

At step 1504, the eNB configures first rate-matching parameters for thefirst resource set and second rate-matching parameters for the secondresource set. In an aspect, the first rate-matching parameters indicatethat the control channel REs are rate-matched around all CSI-RS in thefirst resource set or indicate that the control channel REs arerate-matched around a subset of the CSI-RS in the first resource set. Insuch aspect, the second rate-matching parameters indicate that thecontrol channel REs are rate-matched around all of the CSI-RS on thesecond resource set or indicate that the control channel REs arerate-matched around a subset of the CSI-RS on the second resource set.In another aspect, the first rate-matching parameters indicate that thecontrol channel REs are rate-matched around all CRS in the firstresource set or indicate that the control channel REs are rate-matchedaround a subset of the CRS on the first resource set. In such aspect,the second rate-matching parameters indicate that the control channelREs are rate-matched around all of the CRS on the second resource set orindicate that the control channel REs are rate-matched around a subsetof the CRS in the second resource set. In an aspect, the firstrate-matching parameters are configured via a first RRC configurationand the second rate-matching parameters are configured via a second RRCconfiguration

At step 1506, the eNB transmits the first rate-matching parameters andthe second rate-matching parameters.

At step 1508, the eNB transmits the control channel using the firstresource set and the second resource set, in an aspect, the controlchannel is processed by a receiving device, such as a UE, using at leasta common set of aggregation levels and the first rate-matchingparameters and second rate-matching parameters.

FIG. 16 includes a flow chart 1600 of a method of wirelesscommunication. The method may be performed by an eNB, such as eNB 710 a.At step 1602, the eNB performs rate-matching using a plurality of setsof indices associated with one or more reference signals at a receiver,wherein each set of indices is associated with an eNB.

At step 1604, the eNB transmits downlink control information based onrate matching of at least one of the sets of parameters, the controlinformation including EPDCCH resource elements in a coordinatedmultipoint system.

The references signals may include one or more of CSI-RS and CRS.Performing rate-matching using a plurality of sets of references signalsmay include determining a set of usable resources for transmitting theEPDCCH. Performing rate-matching using a plurality of sets of referencessignals may include rate-matching around all of the indices in theplurality of sets of indices. Performing rate-matching using a pluralityof sets of references signals may include rate-matching around allnonzero-power indices in the plurality of sets of indices. Performingrate-matching using a plurality of sets of references signals mayinclude rate-matching around a set of indices in the plurality of setsof indices that includes a minimum number of indices. Performingrate-matching using a plurality of sets of references signals mayinclude rate-matching around a set of indices in the plurality of setsof indices that includes a maximum number of indices.

In some embodiments, a set of aggregation levels is determined based onthe plurality of sets of indices. The set of aggregation levels may bedetermined independently of the rate-matching. Rate-matching may beperformed around the CSI-RS using a set of parameters that is selectedbased on an aggregation level associated with the selected set ofparameters. In some embodiments, one set of indices relates to CRStransmitted by a serving cell.

FIG. 17 is a conceptual data flow diagram 1700 illustrating the dataflow between different modules/means/components in an exemplaryapparatus 1702. The apparatus may be an eNB. The apparatus includes amodule 1704 that receives UL signals from a UE 1750, a module 1706 thatconfigures a first set of configurations for a PDSCH, each configurationin the first set of configurations defining at least one of a startingsymbol, rate-matching information, or a QCL indication, a module 1708that configures at least a first resource set and a second resource setfor a control channel, configures first rate-matching parameters for thefirst resource set and second rate-matching parameters for the secondresource set, and configures a second set of configurations for anEPDCCH, the second set of configurations being a subset from among thefirst set of configurations, and a module 1710 that transmits the firstset of configurations for the PDSCH and the second set of configurationsfor the EPDCCH, transmits the first rate-matching parameters and thesecond rate-matching parameters, transmits the control channel using thefirst resource set and the second resource set, and/or transmits theEPDCCH.

The apparatus may include additional modules that perform each of thesteps of the algorithm in the aforementioned flow charts of FIGS. 14-16.As such, each step in the aforementioned flow charts of FIGS. 14-16 maybe performed by a module and the apparatus may include one or more ofthose modules. The modules may be one or more hardware componentsspecifically configured to carry out the stated processes/algorithm,implemented by a processor configured to perform the statedprocesses/algorithm, stored within a computer-readable medium forimplementation by a processor, or some combination thereof.

FIG. 18 is a diagram 1800 illustrating an example of a hardwareimplementation for an apparatus 1702′ employing a processing system1814. The processing system 1814 may be implemented with a busarchitecture, represented generally by the bus 1824. The bus 1824 mayinclude any number of interconnecting buses and bridges depending on thespecific application of the processing system 1814 and the overalldesign constraints. The bus 1824 links together various circuitsincluding one or more processors and/or hardware modules, represented bythe processor 1804, the modules 1704, 1706, 1708, and 1710, and thecomputer-readable medium/memory 1806. The bus 1824 may also link variousother circuits such as timing sources, peripherals, voltage regulators,and power management circuits, which are well known in the art, andtherefore, will not be described any further.

The processing system 1814 may be coupled to a transceiver 1810. Thetransceiver 1810 is coupled to one or more antennas 1820. Thetransceiver 1810 provides a means for communicating with various otherapparatus over a transmission medium. The transceiver 1810 receives asignal from the one or more antennas 1820, extracts information from thereceived signal, and provides the extracted information to theprocessing system 1814, specifically the receiving module 1704. Inaddition, the transceiver 1810 receives information from the processingsystem 1814, specifically the transmission module 1710, and based on thereceived information, generates a signal to be applied to the one ormore antennas 1820. The processing system 1814 includes a processor 1804coupled to a computer-readable medium/memory 1806. The processor 1804 isresponsible for general processing, including the execution of softwarestored on the computer-readable medium/memory 1806. The software, whenexecuted by the processor 1804, causes the processing system 1814 toperform the various functions described supra for any particularapparatus. The computer-readable medium/memory 1806 may also be used forstoring data that is manipulated by the processor 1804 when executingsoftware. The processing system further includes at least one of themodules 1704, 1706, 1708, and 1710. The modules may be software modulesrunning in the processor 1804, resident/stored in the computer readablemedium/memory 1806, one or more hardware modules coupled to theprocessor 1804, or some combination thereof. The processing system 1814may be a component of the eNB 610 and may include the memory 676 and/orat least one of the TX processor 616, the RX processor 670, and thecontroller/processor 675.

In one configuration, the apparatus 1702/1702′ for wirelesscommunication includes means for configuring a first set ofconfigurations for a PDSCH, each configuration in the first set ofconfigurations defining at least one of a starting symbol, rate-matchinginformation, or a QCL indication, means for configuring a second set ofconfigurations for an EPDCCH, the second set of configurations being asubset from among the first set of configurations, means fortransmitting the first set of configurations for the PDSCH and thesecond set of configurations for the EPDCCH, means for transmitting theEPDCCH, means for configuring at least a first resource set and a secondresource set for a control channel, means for configuring firstrate-matching parameters for the first resource set and secondrate-matching parameters for the second resource set, means fortransmitting the first rate-matching parameters and the secondrate-matching parameters, means for transmitting the control channelusing the first resource set and the second resource set. Theaforementioned means may be one or more of the aforementioned modules ofthe apparatus 1702 and/or the processing system 1814 of the apparatus1702′ configured to perform the functions recited by the aforementionedmeans. As described supra, the processing system 1814 may include the TXProcessor 616, the RX Processor 670, and the controller/processor 675.As such, in one configuration, the aforementioned means may be the TXProcessor 616, the RX Processor 670, and the controller/processor 675configured to perform the functions recited by the aforementioned means.

It is understood that the specific order or hierarchy of steps in theprocesses disclosed is an illustration of exemplary approaches. Basedupon design preferences, it is understood that the specific order orhierarchy of steps in the processes may be rearranged. Further, somesteps may be combined or omitted. The accompanying method claims presentelements of the various steps in a sample order, and are not meant to belimited to the specific order or hierarchy presented.

The previous description is provided to enable any person skilled in theart to practice the various aspects described herein. Variousmodifications to these aspects will be readily apparent to those skilledin the art, and the generic principles defined herein may be applied toother aspects. Thus, the claims are not intended to be limited to theaspects shown herein, but is to be accorded the full scope consistentwith the language claims, wherein reference to an element in thesingular is not intended to mean “one and only one” unless specificallyso stated, but rather “one or more.” Unless specifically statedotherwise, the term “some” refers to one or more. All structural andfunctional equivalents to the elements of the various aspects describedthroughout this disclosure that are known or later come to be known tothose of ordinary skill in the art are expressly incorporated herein byreference and are intended to be encompassed by the claims. Moreover,nothing disclosed herein is intended to be dedicated to the publicregardless of whether such disclosure is explicitly recited in theclaims. No claim element is to be construed as a means plus functionunless the element is expressly recited using the phrase “means for.”

What is claimed is:
 1. A method of wireless communication at a userequipment (UE), comprising: determining, at the UE, at least a firstresource set and a second resource set configured for an enhancedphysical downlink control channel (EPDCCH); determining, at the UE, acommon set of aggregation levels based on a first set of aggregationlevels for the first resource set and a second, different set ofaggregation levels for the second resource set; determining, at the UE,first rate-matching parameters for the first resource set and secondrate-matching parameters for the second resource set, the firstrate-matching parameters being different from the second rate-matchingparameters; and processing the control channel, at the UE, using atleast the common set of aggregation levels and the first rate-matchingparameters and second rate-matching parameters.
 2. The method of claim1, wherein the determining the common set of aggregation levels for thefirst resource set and the second resource sets comprises determining: afirst number of available resources in the first resource set, a secondnumber of available resources in the second resource set, or both. 3.The method of claim 2, wherein the determining the common set ofaggregation levels further comprises: comparing the first number ofavailable resources to a threshold value, the second number of availableresources to the threshold value, or both; and selecting the common setof aggregation levels based on the comparison.
 4. The method of claim 1,wherein the first rate-matching parameters are configured to rate-matcharound all channel state information reference signals (CSI-RS) in thefirst resource set or rate-match around a subset of the CSI-RS in thefirst resource set, and wherein the second rate-matching parameters areconfigured to rate-match around all of the CSI-RS on the second resourceset or rate-match around a subset of the CSI-RS on the second resourceset.
 5. The method of claim 1, wherein the first rate-matchingparameters are configured to rate-match around all cell-specificreference signals (CRS) in the first resource set or rate-match around asubset of the CRS on the first resource set, and wherein the secondrate-matching parameters are configured to rate-match around all of theCRS on the second resource set or rate-match around a subset of the CRSin the second resource set.
 6. The method of claim 1, wherein the firstrate-matching parameters are determined based on a first radio resourcecontrol (RRC) configuration and the second rate-matching parameters aredetermined based on a second RRC configuration.
 7. An apparatus forwireless communication at a user equipment (UE), comprising: means fordetermining, at the UE, at least a first resource set and a secondresource set configured for an enhanced physical downlink controlchannel (EPDCCH); means for determining, at the UE, a common set ofaggregation levels based on a first set of aggregation levels for thefirst resource set and a second, different set of aggregation levels forthe second resource set; means for determining, at the UE, firstrate-matching parameters for the first resource set and secondrate-matching parameters for the second resource set, the firstrate-matching parameters being different from the second rate-matchingparameters; and means for processing, at the UE, the control channelusing at least the common set of aggregation levels and the firstrate-matching parameters and second rate-matching parameters.
 8. Theapparatus of claim 7, wherein the means for determining the common setof aggregation levels for the first resource set and the second resourcesets determines: a first number of available resources in the firstresource set, a second number of available resources in the secondresource set, or both.
 9. The apparatus of claim 8, wherein the meansfor determining the common set of aggregation levels is furtherconfigured to: compare the first number of available resources to athreshold value, the second number of available resources to thethreshold value, or both; and select the common set of aggregationlevels based on the comparison.
 10. An apparatus for wirelesscommunication at a user equipment (UE), comprising: a memory; and atleast one processor coupled to the memory and configured to: determine,at the UE, at least a first resource set and a second resource setconfigured for an enhanced physical downlink control channel (EPDCCH);determine, at the UE, a common set of aggregation levels based on afirst set of aggregation levels for the first resource set and a second,different set of aggregation levels for the second resource set;determine, at the UE, first rate-matching parameters for the firstresource set and second rate-matching parameters for the second resourceset, the first rate-matching parameters being different from the secondrate-matching parameters; and process, at the UE, the control channelusing at least the common set of aggregation levels and the firstrate-matching parameters and second rate-matching parameters.
 11. Theapparatus of claim 10, wherein the determining the common set ofaggregation levels for the first resource set and the second resourcesets comprises determining: a first number of available resources in thefirst resource set, a second number of available resources in the secondresource set, or both.
 12. The apparatus of claim 11, wherein thedetermining the common set of aggregation levels further comprises:comparing the first number of available resources to a threshold value,the second number of available resources to the threshold value, orboth; and selecting the common set of aggregation levels based on thecomparison.
 13. The apparatus of claim 10, wherein the firstrate-matching parameters are configured to rate-match around all channelstate information reference signals (CSI-RS) in the first resource setor rate-match around a subset of the CSI-RS in the first resource set,and wherein the second rate-matching parameters are configured torate-match around all of the CSI-RS on the second resource set orrate-match around a subset of the CSI-RS on the second resource set. 14.The apparatus of claim 10, wherein the first rate-matching parametersare configured to rate-match around all cell-specific reference signals(CRS) in the first resource set or rate-match around a subset of the CRSon the first resource set, and wherein the second rate-matchingparameters are configured to rate-match around all of the CRS on thesecond resource set or rate-match around a subset of the CRS in thesecond resource set.
 15. The apparatus of claim 10, wherein the firstrate-matching parameters are determined based on a first radio resourcecontrol (RRC) configuration and the second rate-matching parameters aredetermined based on a second RRC configuration.
 16. A non-transitorycomputer-readable medium storing computer executable code for wirelesscommunication at a user equipment (UE), comprising code for:determining, at the UE, at least a first resource set and a secondresource set configured for an enhanced physical downlink controlchannel (EPDCCH); determining, at the UE, a common set of aggregationlevels based on a first set of aggregation levels for the first resourceset and a second, different set of aggregation levels for the secondresource set; determining, at the UE, first rate-matching parameters forthe first resource set and second rate-matching parameters for thesecond resource set, the first rate-matching parameters being differentfrom the second rate-matching parameters; and processing, at the UE, thecontrol channel using at least the common set of aggregation levels andthe first rate-matching parameters and second rate-matching parameters.17. The computer-readable medium of claim 16, wherein the determiningthe common set of aggregation levels for the first resource set and thesecond resource sets comprises determining: a first number of availableresources in the first resource set, a second number of availableresources in the second resource set, or both.
 18. The computer-readablemedium of claim 17, wherein the determining the common set ofaggregation levels further comprises: comparing the first number ofavailable resources to a threshold value, the second number of availableresources to the threshold value, or both; and selecting the common setof aggregation levels based on the comparison.